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Biomedical subjects

A Gray

Publications and source records attributed to A Gray.

At least 199 records · Page 11Linked to original sources

Differential signalling potential of insulin- and IGF-1-receptor cytoplasmic domains.

The human receptors for insulin-like growth factor 1 (IGF-1) and insulin, and two chimeric receptors consisting of ligand-binding, extracellular insulin receptor and intracellular IGF-1 receptor structures, have been expressed in NIH-3T3 fibroblasts. All four receptor types were synthesized, processed and transported to the cell surface to form high-affinity binding sites. All normal and chimeric receptors had an active tyrosine kinase which was regulated by homologous or heterologous ligands respectively. In addition, cell surface receptors were internalized efficiently and subjected to accelerated degradation in the presence of ligand. While all four types of receptor stimulated glucose transport with similar efficiency, they displayed significant differences in their mitogenic signalling potentials. Receptors with an IGF-1 receptor cytoplasmic domain were 10 times more active in stimulating DNA synthesis than the insulin receptor. In NIH-3T3 cells overexpressing wild-type and chimeric receptors, maximal growth responses obtained with IGF-1 or insulin alone were equivalent to those obtained with 10% fetal calf serum. We conclude that in the cell system employed the receptors for IGF-1 and insulin mediate short-term responses similarly, but display distinct characteristics in their long-term mitogenic signalling potentials.

Animals↗

Aboriginal migration to the cities.

"An analysis of actual patterns of Aboriginal migration to the large Australian cities (major urban areas), using data from the 1981 and 1986 Australian Censuses, shows that the major urban areas of New South Wales and Victoria were...losing Aboriginal population through net migration throughout the period 1976 to 1986. At both inter-State level and country-to-city level, any Aboriginal migration flow in one direction tends to be almost cancelled out by a flow of similar size in the opposite direction. However, there are definite age-specific patterns. In particular, there is movement of young single adults to the cities, often counterbalanced by migration of somewhat older adults with their children to the country. Aboriginal migrants have higher levels of labour-force participation than equivalent categories of non-migrants."

Age Factors↗

Identification of an epidermal growth factor receptor homologue in trypanosomes.

Considerable advances have been made in our understanding of cell growth regulation in mammalian cells. In particular, studies on transformed and normal cells have highlighted the contribution of growth factor-related control mechanisms in cell growth regulation. We set out to investigate whether host growth factors are involved in the growth regulation of the parasitic protozoan Trypanosoma brucei. We demonstrate that antibodies to the mammalian epidermal growth factor (EGF) receptor bind to the trypanosome T. brucei and, that these antibodies recognise a surface polypeptide of 135 kDa. This polypeptide is one of only two polypeptides in parasite extracts that bind EGF. Furthermore, EGF modifies protein kinase activity and growth rate of trypanosomes in vitro. These results lead to the conclusion that T. brucei has a surface growth factor receptor with considerable homology to the EGF receptor, and raise the possibility that growth factor interactions similar to those found in mammalian cells are involved in cell growth regulation in trypanosomes.

Animals↗

The questionable physiologic and epidemiologic basis for a male climacteric syndrome: preliminary results from the Massachusetts Male Aging Study.

This paper examines the physiologic and epidemiologic evidence for a widely discussed syndrome termed either 'mid-life crisis', 'male menopause', 'male climacteric', or increasingly, 'andropause'. The paper is divided into 2 parts: (1) a review of evidence from physiologic studies conducted over the last decade that examine endocrine function in aging males; (2) a description of the salient features of an ongoing multidisciplinary epidemiologic study (the Massachusetts Male Aging Study) of a sample of approximately 1700 men aged 40-69 yr, randomly sampled from the general population. This study is markedly different in size and content from studies conducted to date. Preliminary findings suggest that age per se may be a relatively unimportant contributor to endocrine variability and that anthropometrics and life style phenomena may be at least as important.

Adult↗

Validation of the survey of work styles: a profile measure of the type A behaviour pattern.

The present study compares the Type A classification accuracy of the Jenkins Activity Survey (JAS), The Framingham Type A Scale, and a new Type A behaviour pattern (TABP) measure. The Survey of Work Styles (SWS), a self-report measure of the TABP, was developed using a construct approach to scale construction. It consists of six content scales. Impatience, Anger, Work Involvement, Time Urgency, Job Dissatisfaction and Competitiveness. In addition to the six content scales, a seventh scale, Scale A, is comprised of items empirically selected to relate to the Rosenman Structured Interview. In the present study the SWS was found to be significantly related to both the JAS, and the Framingham Type A Scale in a sample of 163 business managers. Median reliability of the SWS subscales was 0.82, and for the total scale 0.90. Discriminant function analysis using cross validational jackknifing procedures resulted in a classification accuracy of 83% of the Type A managers in relation to the Structured Interview. Classification using the SWS was found to correlate significantly higher with the Structured Interview than did either classification with the JAS or with the Framingham Type A Scale. Modal profile analysis yielded three independent bipolar typal dimensions, indicating that a single dimension or classification of the TABP represents an oversimplification of a complex behaviour pattern. These results support the reconceptualization of the TABP in terms of distinct facets and profile patterns.

Adult↗

Influence of tempering and contraction mismatch on crack development in ceramic surfaces.

Tempering of glass produces a state of compressive stress in surface regions which can enhance the resistance to crack initiation and growth. The objective of this study was to determine the influence of tempering on the sizes of surface cracks induced within the tempered surfaces of opaque porcelain-body porcelain discs, with contraction coefficient differences (alpha O-alpha B) of +3.2, +0.7, 0.0, -0.9, and -1.5 ppm/degrees C. We fired the discs to the maturing temperature (982 degrees C) of body porcelain and then subjected them to three cooling procedures: slow cooling in a furnace (SC), fast cooling in air (FC), and tempering (T) by blasting the body porcelain surface with compressed air for 90 s. We used body porcelain discs as the thermally compatible (delta alpha = 0) control specimens. We measured the diameters of cracks induced by a microhardness indenter at an applied load of 4.9 N at 80 points along diametral lines within the surface of body porcelain. The mean values of the crack diameters varied from 75.9 microns (delta alpha = -1.5 ppm/degrees C) to 103.3 microns (delta alpha = +3.2 ppm/degrees C). The results of ANOVA indicate that significant differences in crack dimensions were controlled by cooling rate, contraction mismatch, and their combined effect (p less than 0.0001). Multiple contrast analysis (Tukey's HSD Test) revealed significantly lower (p less than 0.05) crack sizes for tempered specimens compared with those of fast-cooled and slow-cooled specimens.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

Mammographic screening for breast cancer: prospects for New Zealand.

The Cancer Society and the Department of Health invited a working group to make recommendations on screening by mammography. Mammography offers the best opportunity for preventing deaths from breast cancer. Randomised trials suggest that mortality can be reduced by about 30% in women over 50; the value of routine mammography in younger women is still uncertain. Apart from financial costs, the main drawback of mammography is that many women receive unnecessary investigation because of false-positive results. Careful design and monitoring of programmes is essential to ensure that the benefits of screening outweigh the disadvantages. In New Zealand there is a shortage of radiologists, pathologists, and clinicians who are skilled in the specialised techniques required for the screening of asymptomatic women. Decisions about routine screening should be delayed until pilot programmes have been established, with assessment of their effectiveness, economic efficiency, and social acceptability. Recommendations for the design of such programmes are made.

Adult↗

Polysaccharide storage myopathy.

In a woman with a slowly progressive adult onset proximal myopathy, muscle biopsy showed storage of PAS positive material in type 1 fibers. This material consisted of a branched chain polysaccharide associated with a mucoprotein. No abnormality of glycogen-pathway enzymes was detected. This suggested that this polysaccharide accumulation occurred because the polysaccharide was laid down in a non-bioavailable form. The clinical and histochemical features in this patient and in the few similar reported cases indicate that polysaccharide storage myopathy is a distinct entity that is allied to the glycogen storage myopathies.

Electromyography↗

Knibbs and Wickens.

"A recent claim that the first Commonwealth Statistician [of Australia], Sir George Knibbs, was not the real author of the work 'The Mathematical Theory of Population' is shown to conflict with overwhelming evidence that Knibbs was the author in fact, as well as in name. Resolution of this question gives a keen appreciation of the work of Knibbs and his successor, Mr. Charles Wickens."

Australia↗

Progressive loss of fibronectin-mediated opsonic activity in plasma cryoprecipitate with storage. Role of fibronectin fragmentation.

Septic injured patients often manifest a deficiency of plasma fibronectin. Several studies have shown improvements in organ function in such patients following infusion of fibronectin-rich plasma cryoprecipitate, while other studies found no improvement. One explanation for these differences may be the use of plasma cryoprecipitate which has been stored for various time intervals prior to its use as a source of fibronectin. This investigation tested the hypothesis that the opsonic activity of fibronectin in cryoprecipitate may decline with increased storage duration. Using a bioassay of opsonic activity, we evaluated human plasma cryoprecipitate that was stored at either -20 or -80 degrees C for various intervals (2 weeks to 12 months) after its preparation from fresh donor plasma. Our findings demonstrated that the opsonic activity of fibronectin in cryoprecipitate declined with increasing time of storage. Significant loss (p less than 0.05) of opsonic activity was first evident after 2 months of storage. Storage at -80 degrees C did not prevent this decline in opsonic activity as compared to storage at -20 degrees C. Immunoblot analysis revealed extensive fragmentation of the dimeric fibronectin (440 kdaltons) and the presence of lower molecular weight fragments in 4- to 12-month-old plasma cryoprecipitate. Therefore, plasma cryoprecipitate of varying ages (storage time) when used as a source of fibronectin for replacement therapy to support phagocytic function in septic injured patients may result in different fibronectin-mediated responses. The decline in activity may be due, in part, to fragmentation of the fibronectin molecule.

Biological Assay↗

Ultrastructural changes in internal anal sphincter in neurogenic faecal incontinence.

The ultrastructural features of the internal anal sphincter (IAS) muscle were studied in biopsies from five patients with neurogenic anorectal incontinence and six control subjects undergoing anorectal excision for cancer, or for inflammatory bowel disease. In the patients with idiopathic neurogenic anorectal incontinence the internal anal sphincter showed loss of smooth muscle cells, disruption of the normal relationships of the remaining cells, stretching of elastic tissue, and increased collagen fibril content. These ultrastructural changes in the morphology of the internal anal sphincter, although probably not the primary cause of faecal incontinence, have functional relevance in the clinical syndrome, as shown by the reduction in resting anal canal pressure found in some patients with this syndrome.

Adult↗

Delayed crack development in porcelain due to incompatibility stress.

Delayed failure of metal-ceramic restorations due to static fatigue can occur when residual tensile stress is present in porcelain, even in the absence of intra-oral forces. Fixed-partial-denture (FPD) specimens and semicircular arch specimens with gapped cross-arch segments were employed to characterize the potential of two incompatible metal-ceramic systems for producing delayed crack development and to determine the relative sensitivity of these test designs as monitors of incompatibility stresses which resulted from thermal contraction differences between a nickel-chromium alloy and three experimental porcelains. The arch specimens were judged to be more suitable for analysis of residual stresses because of the larger magnitude of gap changes at each procedural change. However, the FPD specimens exhibited earlier evidence of delayed crack growth in porcelain when the thermal contraction coefficient of the metal exceeded that of the porcelain by either 1.7 X 10(-6)/degrees C or 2.2 X 10(-6)/degrees C. For these two states of incompatibility, the agreement between experimental gap values for the arch specimens and the gap values predicted from composite strip equations was excellent.

Chemical Phenomena↗

Disposition of bemitradine, a renal vasodilator and diuretic, in man.

1. 14C-Bemitradine (50 mg) was rapidly and efficiently absorbed (approximately 89%) in man following a single oral dose, as a solution in gelatine capsules. Peak 14C levels of 895 +/- 154 ng equiv./ml (mean +/- S.E.M.) were reached within 2 h, and declined with half-lives of 1.07 +/- 0.25 and 13.0 +/- 5.6h. 2. No bemitradine was detected in plasma, but peak concn. (124 +/- 29 ng/ml) of its desethyl metabolite were reached at 1.05 +/- 0.28 h, and declined with a half-life of 1.32 +/- 0.08 h. 3. Desethylbemitradine was rapidly metabolized to its ether glucuronide, a phenol and a dihydrodiol which were also present as glucuronide conjugates. The glucuronides were the major compounds in plasma from 2 h after drug administration. 4. Excretion in 5 days amounted to 88.8 +/- 2.3% and 10.4 +/- 2.1% dose in urine and faeces respectively. No bemitradine or desethylbemitradine were excreted unchanged. 8-(2-Hydroxyethyl)-7-(3,4- dihydroxycyclohexa-1,5-dienyl)-1,2,4-triazolo-1,5c-pyrimidin e-5-amine (E; 17% dose); 8-(2-hydroxyethyl)-7-(4-hydroxyphenyl)-1,2,4-triazolo-1,5c- pyrimidine-5-amine (F; 4% dose), their glucuronides (A, 19% dose and B, 6% dose respectively), desethylbemitradine glucuronide (D, 25% dose) and an unidentified metabolite (C, 12% dose) were excreted in urine. Compound F was the major faecal metabolite.

Absorption↗

Tissue-specific and developmentally regulated transcription of the insulin-like growth factor 2 gene.

Transcription of the rat and human IGF-2 gene loci is unusually complex. The pattern of expression of these genes varies both between tissues and within a given tissue during different stages of development. Alternative splicing or possibly transcriptional initiation events generate variant IGF-2 mRNAs that contain different 5'-untranslated leader sequences. These leader exon sequences are shared with non-IGF-2 mRNAs. Certain noncoding IGF-2 gene sequence elements are transcribed extensively and are found in multiple copies elsewhere in the human genome. Furthermore, IGF-2 mRNA levels are particularly high in a variety of human malignancies.

Age Factors↗

Air rifle breech injuries to digits: a preventable hazard.

The obvious injuries attributable to air rifles, namely those caused by pellets, are common and well documented (Batch, 1981; Reid, 1974; Rawson, 1965; Hutchinson, 1981). The author has encountered a series of injuries from air rifles involving a different mechanism. These commonly involve the digits, often in young people, and require considerable hospital time and resources in their treatment. They are essentially preventable.

Adult↗